Study On CO₂Electrochemical Reduction With Pb Loaded Gas Diffusion Electrode

The usage and conversion of CO₂not only can resolve the environmentalproblems, but also obtains the corresponding useful organic compounds, achieving therecycling of resources. In all kinds of conversion approaches, electrochemicalreduction as a new green method is being paid extensive attention. In our study, CO₂was electroreduced to formic acid with Pb loaded gas diffusion electrode in KHCO₃solution.The isometric impregnation and hydrogen reduction were applied to preparePb/C catalyst with cubic crystalline phase, which was mixed with acetylene black andPTFE to fabricate Pb loaded gas diffusion electrode. The polarization curve andproduction analysis were employed to investigate catalytic layer fabricationconditions. The results indicated that the electrode achieved the optimal performancewhen the proportion of acetylene black and PTFE were15%and25%, layer thicknessand forming pressure were0.4mm and10MPa.The optimum fabrication conditions of gas diffusion layer were also investigatedby polarization curve, chronoamperometry curve and permeability test. The idealfabrication parameters were shown as follows: PTFE proportion in this layer was30%,the mass ratio between acetylene black and Na₂SO₄was2.5:1, and the layer thicknesswas0.4mm.By investigating the reaction conditions including electrolyte concentration andreduction potential, it was found that when the electrolyte concentration maintained at0.5mol·L^-1, the gas diffusion electrode showed the best performance. Moreover, boththe formic acid concentration and final current efficiency increased along with thenegative move of potential, and achieved their maximum values at-2.0V.